From f0aac4b50fa4a34d267798338ac0ca4898c07f3e Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Thu, 22 Dec 2011 19:37:16 +0100
Subject: [PATCH] flow: actor class

---
 migen/flow/__init__.py |   0
 migen/flow/actor.py    | 114 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 114 insertions(+)
 create mode 100644 migen/flow/__init__.py
 create mode 100644 migen/flow/actor.py

diff --git a/migen/flow/__init__.py b/migen/flow/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/migen/flow/actor.py b/migen/flow/actor.py
new file mode 100644
index 000000000..774a9229a
--- /dev/null
+++ b/migen/flow/actor.py
@@ -0,0 +1,114 @@
+from migen.fhdl.structure import *
+from migen.corelogic.optree import optree
+
+class SchedulingModel:
+	COMBINATORIAL, SEQUENTIAL, PIPELINE, DYNAMIC = range(6)
+	
+	def __init__(self, model, latency=1):
+		self.model = model
+		self.latency = latency
+	
+	def __str__(self):
+		if self.model == SchedulingModel.COMBINATORIAL:
+			return "<SchedulingModel: COMBINATORIAL>"
+		elif self.model == SchedulingModel.SEQUENTIAL:
+			return "<SchedulingModel: SEQUENTIAL({0})>".format(self.latency)
+		elif self.model == SchedulingModel.PIPELINE:
+			return "<SchedulingModel: PIPELINE({0})>".format(self.latency)
+		elif self.model == SchedulingModel.DYNAMIC:
+			return "<SchedulingModel: DYNAMIC>"
+		else:
+			raise AttributeError
+
+class Sink:
+	def __init__(self, actor, token):
+		self.actor = actor
+		self.token = token
+		self.stb_i = Signal()
+		self.ack_o = Signal()
+
+class Source:
+	def __init__(self, actor, token):
+		self.actor = actor
+		self.token = token
+		self.stb_o = Signal()
+		self.ack_i = Signal()
+
+def _control_fragment_comb(l_stb_i, l_ack_o, l_stb_o, l_ack_i):
+	en = Signal()
+	comb = [en.eq(optree('&', l_stb_i + l_ack_i))]
+	comb += [o.eq(en) for o in l_ack_o + l_stb_o]
+	return Fragment(comb)
+
+def _control_fragment_seq(latency, l_stb_i, l_ack_o, l_stb_o, l_ack_i, trigger):
+	ready = Signal()
+	timer = Signal(BV(bits_for(latency)))
+	comb = [ready.eq(timer == 0))]
+	sync = [
+		If(trigger,
+			timer.eq(latency)
+		).Elif(~ready,
+			timer.eq(timer - 1)
+		)
+	]
+	
+	nsources = len(l_stb_o)
+	mask = Signal(BV(nsources))
+	sync.append(If(trigger, mask.eq(0)).Else(mask.eq(mask | Cat(*l_ack_i))))
+
+	comb.append(Cat(*l_stb_o).eq(Replicate(len(l_stb_o), ready) & ~mask))
+	comb.append(Cat(*l_ack_o).eq(Replicate(len(l_ack_o), trigger)))
+	
+	stb_all = Signal()
+	comb.append(stb_all.eq(optree('&', l_stb_i)))
+	comb.append(trigger.eq(ready & stb_all & ((mask | Cat(*l_ack_i)) == Replicate(nsources, 1))))
+
+	return Fragment(comb, sync)
+
+def _control_fragment_pipe(latency, l_stb_i, l_ack_o, l_stb_o, l_ack_i, pipe_ce):
+	stb_all = Signal()
+	comb = [stb_all.eq(optree('&', l_stb_i))]
+	valid = Signal(BV(latency))
+	if latency > 1:
+		sync = [If(pipe_ce, valid.eq(Cat(stb_all, valid[1:])))]
+	else:
+		sync = [If(pipe_ce, valid.eq(stb_all))]
+	last_valid = valid[latency-1]
+	
+	nsources = len(l_stb_o)
+	mask = Signal(BV(nsources))
+	sync.append(If(pipe_ce, mask.eq(0)).Else(mask.eq(mask | Cat(*l_ack_i))))
+	
+	comb.append(Cat(*l_stb_o).eq(Replicate(len(l_stb_o), last_valid) & ~mask))
+	comb.append(Cat(*l_ack_o).eq(Replicate(len(l_ack_o), pipe_ce)))
+	
+	comb.append(pipe_ce.eq(~last_valid | ((mask | Cat(*l_ack_i)) == Replicate(nsources, 1))))
+	
+	return Fragment(comb, sync)
+
+class Actor:
+	def __init__(self, scheduling_model, sinks, sources):
+		self.scheduling_model = scheduling_model
+		self.sinks = sinks
+		self.sources = sources
+		if self.scheduling_model.model == SEQUENTIAL:
+			self.trigger = Signal()
+		elif self.scheduling_model.model == PIPELINE:
+			self.pipe_ce = Signal()
+	
+	def get_control_fragment():
+		l_stb_i = [e.stb_i for e in self.sinks]
+		l_ack_o = [e.ack_o for e in self.sinks]
+		l_stb_o = [e.stb_o for e in self.sources]
+		l_ack_i = [e.ack_i for e in self.sources]
+		if self.scheduling_model.model == COMBINATORIAL:
+			return _control_fragment_comb(l_stb_i, l_ack_o, l_stb_o, l_ack_i)
+		elif self.scheduling_model.model == SEQUENTIAL:
+			return _control_fragment_seq(self.scheduling_model.latency, l_stb_i, l_ack_o, l_stb_o, l_ack_i, self.trigger)
+		elif self.scheduling_model.model == PIPELINE:
+			return _control_fragment_pipe(self.scheduling_model.latency, l_stb_i, l_ack_o, l_stb_o, l_ack_i, self.pipe_ce)
+		elif self.scheduling_model.model == DYNAMIC:
+			raise NotImplementedError("Actor classes with dynamic scheduling must overload get_control_fragment")
+	
+	def get_process_fragment():
+		raise NotImplementedError("Actor classes must overload get_process_fragment")